The prior art patent to Rendler, U.S. Pat. No. 3,104,293, reveals a hospital call signal switch having a closed pneumatic bulb in conjunction with a moveable cylinder. Movement of the cylinder closes contacts within an electrical jack which is plugged into the conventional nurse call system. The pneumatic bulb, which is typical of most actuators provided, is said to be actuated by an elbow, knee, foot or other part of the body and essentially is provided to isolate the patient from an electrical system. This type of bulb actuated system requires considerable movement and squeezing of the bulb and a required large pressure build up in the system to actuate it. This voluntary muscular control to effectively actuate a system such as this is impossible for the paralyzed or arthritic patient.
The patent to Panzenhagen, U.S. Pat. No. 2,838,629, shows another bulb-actuated, remote switching device which provides a mechanism for latching the contacts in a closed position until the switch is reset. Multiple contacts are disclosed in this device for providing signals in one or more different locations.
The patent to Schirmer, U.S. Pat. No. 1,799,126, shows a hospital call switch having a housing which is plugged directly into a corresponding wall outlet. A conventional sealed pneumatic bulb and tube are connected to a closed diaphram chamber within the housing. This provides a closed and sealed pneumatic actuation system which is typical of all known prior art.